This invention relates to a mobile type gantry crane.
Straddle type gantry cranes are commonly employed for lifting and moving large bulky objects, such as shipping containers, structural members, modular building sections, heavy machinery and equipment and the like. Such devices are well known and generally include a pair of inverted U-shaped gantries comprising cross beams spanning vertical columns which are supported at their lower ends on wheels or truck assemblies. The two gantry assemblies are interconnected by spaced side members and may include hoists supported from the cross beams by means of a trolley. This permits the load to be elevated and traversed laterally.
Mobile type cranes must be sufficiently maneuverable for being positioned above the load prior to elevation and for transporting the load from one location to another. When operated in a shop or storage area, for example, the crane will normally move longitudinally up and down an aisle and in addition, laterally between aisles. This requires a relatively flexible steering assembly. In addition, because of the large weight involved, particularly when a load is being transported, improper wheel orientation can cause inordinate stresses.